Self-threading sewing machine needle

ABSTRACT

A sewing machine needle is disclosed in which a threading slot extends lengthwise along the needle blade and opens onto the needle eye. A twist is formed in the needle blade so that the portions of the needle blade which are separated by the threading slot are wrapped about each other and stabilized thereby.

United States Patent Zocher Feb. 29, 1972 [54] SELF-THREADING SEWING MACHINE 1,441,575 1/1923 Granger ..112/224 NEEDLE 2,295,193 9/1942 Alexander ..112 224 [72] Inventor: Josef Zocher, Haaren, Aachen, Germany Primary Examiner james R- Boler [73] Assignee: The Singer Company, New York, NY. Attorney-Marshall J. Breen, Chester A. Williams, Jr. and

Robert E. Smith [22] Filed: Sept. 24, 1970 v a a at [21] Appl. No.: 75,055 [57] ABSTRACT A sewing machine needle is disclosed in which a threading slot [52] 11.8. C1 ..112/224 exten engthwise along the needle blade and opens onto the 51] 11m. 131. ..D05b 87/00 needle y A twist is formed n the dl lad s that the 58 Field ofSear-ch ..2/222,223,224 Portions of the needle blade which are Separated y the threading slot are wrapped about each other and stabilized [56] References Cited thereby- H UNITED STATES PATENTS 1,073,140 9/1913 Kendig ....1l2/224 8 (Ilaims, 7 Drawing Figures PATENTEBFEB 29 I972 Fig.7

Fig. 6

INVENTOR. Josef 20 char 5%., ATTORNEY WITNESS= SELF-THREADING SEWING MACHINE NEEDLE BACKGROUND OF THE INVENTION Previously known self-threading needles which include a threading slot extending upwardly from the needle eye to a level above that which the needle penetrates the work, have not proven satisfactory in use for a variety of reasons. Most are unsatisfactory because the needle blade is seriously weakened. As exemplified in the disclosure of the US. Pat. of .l. W. Alexander, No. 2,295,193, issued Sept. 8, 1942, the thread directing fin, similar to that used with most known selfthreading needles of this type, extends alongside the needle blade and is unstabilized and free to vibrate objectionally relatively to the blade.

The US. Pat. of Granger, No. 1,441,575, issued Jan. 9, 1923, discloses a known form of construction in which a thread-directing wire is attached to the needle blade alongside or below the needle eye and extends upwardly adjacent to the needle blade. A number of configurations are disclosed for the thread-directing wire whereby the wire might gain a degree of support from the needle blade. These disclosures involve the extremely difficult requirement that the wire must be subjected to a different or separate series of formative operations from the needle blade and, therefore, the needle construction which is disclosed is not commercially practical.

SUMMARY OF THE INVENTION It is an object of this invention to provide a self-threading sewing machine needle of the type having a threading slot extending from the needle eye to a level above that which the needle penetrates the work, which is commercially practical to construct and in which weakening of the needle blade is minimized.

The object of this invention is attained by providing a twist in the blade of a self-threading sewing machine needle having a lengthwise threading slot. The spirally entwined portions of the needle blade are mutually strengthened by the twist and the fin or needle blade portion, which yields to pass a sewing thread into the needle eye, is stabilized thereby so that lateral vibration is prevented by the interlocking action provided by the twist.

The interlocking action provided by the twist formed in the divided needle blade is enhanced when the threading slot is formed exceedingly narrow and preferably is substantially closed as by a pressing operation on the needle blade after the cutting of the threading slot.

When the threading slot is substantially closed a need arises for an appreciable flexibility of the portions of the needle blade in order to admit a sewing thread along the threading slot. Under these circumstances, a tapered configuration of the thread-carrying needle eye is desirable. It has been found that a tapered needle eye can be made longer commensurate with adequate control of the thread during sewing and the longer eye enhances the flexibility of the portions of the needle blade which are divided by the threading slot.

With the above and additional objects and advantages in view as will hereinafter appear, this invention is illustrated in the accompanying drawing of a preferred embodiment in which:

FIG. 1 represents an elevational view of a sewing machine needle embodying this invention as viewed from a position looking through the needle eye and with the width of the threading slot exaggerated for clarity;

FIG. 2 represents an elevational view taken from the lefthand side of the sewing machine needle of FIG. 1 with portions illustrated in cross section and with the width of the threading slot exaggerated;

FIG. 3 is an enlarged cross sectional view of the needle taken substantially along line 33 of FIG. 2 without exaggeration of the width of the threading slot and including a representation of a thread being directed into the thread inlet slot;

FIG. 4 is an enlarged cross sectional view of the needle taken substantially along line 44 of FIG. 2 and including a representation of a thread being directed along the threading slot;

FIG. 5 is an enlarged cross-sectional view of the needle taken substantially along line 5-5 of FIG. 2 without exaggeration of the width of the threading slot;

FIG. 6 is an enlarged elevational view of a fragment of a semifinished needle in accordance with this invention viewed in a direction looking through the needle eye; and

FIG. 7 is an enlarged elevational view of the same fragment of the needle as shown in FIG. 6 but showing the needle in finished form.

As illustrated in the drawings, the needle of this invention is formed with a shank 11 which may be slabbed as at 12 for orientation in a sewing machine needle clamp. From the shank, the needle tapers to a blade portion 13 which, at the opposite end from the shank, is formed with a pointed extremity l4. Adjacent to the pointed extremity the needle blade is formed with a transverse thread-carrying eye 15 through which a sewing thread must extend during sewing operation. The needle, as thus far described, has a conformation and general relationship of parts which is well known in conventional sewing machine needles so that the needle of this inven tion is exchangeable with ordinary needles in a sewing machine.

It is conventional in sewing machine needle construction to provide a long thread-accommodating groove from the needle eye toward the shank only on that side of the needle from which the thread extends to the supply spool. The other side of the needle, from which the thread extends to the work, conventionally has at most only a short groove. The purpose of the conventional thread accommodating long groove arrangement is to discourage thread loop formation on the thread supply limb side of the needle by providing clearance and freedom for thread movement in the long groove while encouraging thread loop formation on the thread work limb side of the needle where the sewing machine loop taker must seize aloop.

In the needle of this invention, a long thread accommodat ing groove 20 is formed from the needle eye 15 to the needle shank 11 on that side of the needle from which the thread extends to the supply spool. The long thread-accommodating groove 20 is preferably of a size and width fully comparable to the long groove of a similar size conventional needle. At the opposite side of the needle of this invention, i.e., on the side from which the sewing thread extends to the work, a long groove 25 is formed in the blade from the needle eye to the shank. The long groove 25, however, is preferably made much narrower than the groove 20 and is offset to one side of the center of the needle section as shown in FIGS. 3, 4 and 5. The narrow long groove 25 facilitates the introduction of thread into the eye of the needle in accordance with this invention as will be described hereinbelow.

In order to facilitate insertion of thread into the needle eye 15, the needle blade 13 is split into two lateral segments 30 and 31 by a threading slot 40 which extends from the juncture of the needle blade 13 with the shank 11 to the needle eye 15. As illustrated in FIGS. 3, 4 and S, the threading slot 40 is formed along one edge of and opens onto each of the thread accommodating grooves 20 and 25. Since the threading slot 40 is arranged toward one side of the needle blade, the lateral segment 31 defined thereby will be considerably smaller in cross sectional extent than the segment 30.

Adjacent to the juncture of the needle shank 11 and the needle blade 13, a transverse thread inlet slot 50 is formed across the needle sufiiciently deep as to open onto the threading slot 40 thus providing a path for the thread from exteriorly of the needle through the inlet slot 50 and along the threading slot 40 to the needle eye.

To stabilize the needle blade segment 31, the entire needle blade 13 is twisted as shown in the drawings. FIGS. 1 and 2 illustrate a preferred form of this invention in which a twist of greater than 180 has been imparted to only that portion of the needle blade immediately adjacent to the needle shank 11. As shown, the twist occurs over less than half the distance between the thread inlet slot 50 and the needle eye 15. This form of construction is preferable because the free extremity of the blade segment 31 is interlocked with the segment 30 and stabilized thereby and the lower portion of the thread accommodating groove 20 remains straight and can accept the supply limb of thread to discourage loop formation on that side of the needle. A twist of greater than 180 proves most effective in stabilizing the needle blade segments with a twist of 185 to 200 about the lengthwise axis of the needle being ideal; however, twists of less than 180 provide proportionate advantages and are superior to prior art constructions which have no twist whatever.

In FIGS. 1 and 2, the threading slot is purposely illustrated wider than the slot preferably is dimensioned in a finished needle; and this exaggeration is purposely done in order to illustrate the construction more clearly. In practice, a very narrow threading slot 40 may be provided by first cutting the slot 40 using a cutting wheel or the like, with a considerable width as shown in FIG. 6 and then subsequently pressing the needle blade 13 substantially completely closing the slot 40 as shown in FIG. 7. The needle blade 13 may be formed initially wider or with a larger diameter to compensate for the subsequent reduction in size when the slot 40 is pressed closed.

When the thread is introduced to the threading slot 40, the lateral segments 30 and 31 of the needle blade must flex apart particularly when the threading slot 40 has been pressed closed. The eye of the needle lends flexibility to the lateral segments 30 and 31 and, in particular, an eye of teardrop or tapered shape, which can be made proportionately longer than a round or oval shaped eye, can be used to lend flexibility to the lateral segments 30 and 31 of the needle.

The threading sequence when using the needle of this invention is indicated in the cross sectional views of FIGS. 3, 4 and 5. In these FIGS., the width of the threading slot 40 is not exaggerated, i.e., it is shown substantially closed in the absence of thread therein as in FIGS. 3 and 5 and is shown forced apart by the thread in FIG. 4.

To thread the needle eye 15, the thread T is first held transversely across the needle blade 13 adjacent to the shank 11 and is directed into the thread inlet slot 50 as shown in FIG. 3. By maintaining a slight tension on the thread, it may easily be forced from the thread inlet slot 50 downwardly into the threading slot 40. When the thread has been drawn into the needle eye, the lateral segments 30 and 31 of the needle blade will return into substantial engagement as shown in FIG. 5 thus effectively to deter escape of the thread from the eye 15 back into the threading slot 40.

As shown in FIGS. 3, 4 and 5, the threading slot 40 extends across the needle blade between the grooves and 25. As a thread is drawn along the slot 40, therefore, it will contact only a very narrow section of the needle blade between the grooves 20 and and the frictional resistance to introduction of a thread to the eye will be minimized.

In the preferred embodiment shown, since a twist of slightly greater than 180 is imparted to the entire needle blade 13, the thread must be introduced to the thread inlet slot 50 with an orientation opposite that which is desired when the thread is finally positioned in the needle eye. Thus, since the thread limb which extends to the supply spool must extend from the needle eye, as viewed in FIG. 1, toward the viewer, that limb extending to the supply spool must be directed from behind the needle as viewed in FIG. 1 when being introduced into the inlet slot 50.

As a modification, successive twists in opposite directions may be made along the length of the needle blade so that the blade segments will be interlocked for added stability and yet the thread can be oriented at the start of needle threading precisely as it will be oriented when shifted into the needle eye. The twist, which may be of either clockwise or counterclockwise direction, and which may extend over just the uppermost portion of the needle blade or over practically the entire distance between the shank and the needle eye, serves a number of essential purposes influencing the characteristics of the needle during thread insertion and during sewing. First, the twist locks the free upper extremity of the needle blade segments 30 and 31 together and keeps the smaller segment 31 from vibrating laterally. Second, the twist aids in urging the slot 40 into a closed position. Third, the twist, by providing for mutual support of the needle blade segments 30 and 31, strengthens the needle.

Having set forth the nature of this invention, what is claimed l. A self-threading sewing machine needle including a shank adapted to be clamped to the sewing machine, a blade extending from the shank and terminating in a pointed extremity formed with a thread-carrying eye, said blade being formed with a lengthwise thread accommodating groove extending from said thread-carrying eye toward said shank, a threading slot formed through said needle blade and extending lengthwise from adjacent to said shank into said thread-carrying eye, said threading slot opening at one side of said needle blade into said thread-accommodating groove, a thread inlet slot formed transversely across said needle blade adjacent said shank and opening onto said threading slot, and said needle blade along the length of said threading slot being formed with a twist about the longitudinal axis of the needle blade.

2. A self-threading sewing machine needle as set forth in claim 1 in which said twist formed in said needle blade extends continuously and in one direction for an angle of greater than about the longitudinal axis of the needle blade.

3. A self-threading sewing machine needle as set forth in claim 1 in which said twist in the needle blade extends only from said thread inlet slot adjacent the needle shank to a point along said needle blade less than half the distance between said thread inlet slot and the thread-carrying needle eye.

4. A self-threading sewing machine needle as set forth in claim 1 in which said needle blade is formed with a pair of thread-accommodating grooves one at each side of the needle blade and each groove extending from said thread-carrying eye to said shank, and in which said threading slot opens at each side of said needle blade into a respective one of said thread-accommodating grooves.

5. A self-threading sewing machine needle as set forth in claim 4 in which said threading slot opens along one extreme edge of each of said thread-accommodating grooves.

6. A self-threading sewing machine needle as set forth in claim 4 in which one of said thread-accommodating grooves is appreciably narrower than the other groove.

7. A self-threading sewing machine needle as set forth in claim 1 in which said thread-carrying eye is formed with tapered sides which diverge from the pointed extremity of the needle and are widest at the eye extremity into which said threading slot opens.

8. A self-threading sewing machine needle as set forth in claim 1 in which said threading slot is formed with sidewalls which are arranged substantially in touching relationship in the absence of a thread forced therebetween. 

1. A self-threading sewing machine needle including a shank adapted to be clamped to the sewing machine, a blade extending from the shank and terminating in a pointed extremity formed with a thread-carrying eye, said blade being formed with a lengthwise thread accommodating groove extending from said thread-carrying eye toward said shank, a threading slot formed through said needle blade and extending lengthwise from adjacent to said shank into said thread-carrying eye, said threading slot opening at one side of said needle blade into said thread-accommodating groove, a thread inlet slot formed transversely across said needle blade adjacent said shank and opening onto said threading slot, and said needle blade along the length of said threading slot being formed with a twist about the longitudinal axis of the needle blade.
 2. A self-threading sewing machine needle as set forth in claim 1 in which said twist formed in said needle blade extends continuously and in one direction for an angle of greater than 180* about the longitudinal axis of the needle blade.
 3. A self-threading sewing machine needle as set forth in claim 1 in which said twist in the needle blade extends only from said thread inlet slot adjacent the needle shank to a point along said needle blade less than half the distance between said thread inlet slot and the thread-carrying needle eye.
 4. A self-threading sewing machine needle as set forth in claim 1 in which said needle blade is formed with a pair of thread-accommodating grooves one at each side of the needle blade and each groove extending from said thread-carrying eye to said shank, and in which said threading slot opens at each side of said needle blade into a respective one of said thread-accommodating grooves.
 5. A self-threading sewing machine needle as set forth in claim 4 in which said threading slot opens along one extreme edge of each of said thread-accommodating grooves.
 6. A self-threading sewing machine needle as set forth in claim 4 in which one of said thread-accommodating grooves is appreciably narrower than the other groove.
 7. A self-threading sewing machine needle as set forth in claim 1 in which said thread-carrying eye is fOrmed with tapered sides which diverge from the pointed extremity of the needle and are widest at the eye extremity into which said threading slot opens.
 8. A self-threading sewing machine needle as set forth in claim 1 in which said threading slot is formed with sidewalls which are arranged substantially in touching relationship in the absence of a thread forced therebetween. 